diff --git a/vlib/compiler/cc.v b/vlib/compiler/cc.v
index cd29930485..2c9a8755b3 100644
--- a/vlib/compiler/cc.v
+++ b/vlib/compiler/cc.v
@@ -174,9 +174,9 @@ fn (v mut V) cc() {
 				println('$path not found... building module $imp')
 				if path.ends_with('vlib/ui.o') {
 					println('copying ui...')
-					os.cp('$vdir/thirdparty/ui/ui.o', path)
-					os.cp('$vdir/thirdparty/ui/ui.vh', v_modules_path +
-							'/vlib/ui.vh')
+					_ = os.cp('$vdir/thirdparty/ui/ui.o', path) or { panic('error copying ui files') }
+					_ = os.cp('$vdir/thirdparty/ui/ui.vh', v_modules_path +
+							'/vlib/ui.vh')  or { panic('error copying ui files') }
 					
 				}	else {
 					os.system('$vexe build module vlib${os.path_separator}$imp_path')
diff --git a/vlib/compiler/gen_c.v b/vlib/compiler/gen_c.v
index 13f71c1ef0..317dd2aada 100644
--- a/vlib/compiler/gen_c.v
+++ b/vlib/compiler/gen_c.v
@@ -11,12 +11,15 @@ fn (p mut Parser) gen_or_else(pos int) string {
 }
 */
 
+
 // returns the type of the new variable
 fn (p mut Parser) gen_var_decl(name string, is_static bool) string {
 	// Generate expression to tmp because we need its type first
 	// `[typ] [name] = bool_expression();`
 	pos := p.cgen.add_placeholder()
+	p.is_var_decl = true
 	mut typ := p.bool_expression()
+	p.is_var_decl = false
 	if typ.starts_with('...') { typ = typ[3..] }
 	//p.gen('/*after expr*/')
 	// Option check ? or {
@@ -68,10 +71,13 @@ fn (p mut Parser) gen_blank_identifier_assign() {
 	is_indexer := p.peek() == .lsbr
 	is_fn_call, next_expr := p.is_next_expr_fn_call()
 	pos := p.cgen.add_placeholder()
+	p.is_var_decl = true
 	typ := p.bool_expression()
+	p.is_var_decl = false
 	if !is_indexer && !is_fn_call {
 		p.error_with_token_index('assigning `$next_expr` to `_` is redundant', assign_error_tok_idx)
 	}
+	// handle or
 	if p.tok == .key_orelse {
 		p.gen_handle_option_or_else(typ, '', pos)
 	} else {
@@ -93,6 +99,7 @@ fn (p mut Parser) gen_handle_option_or_else(_typ, name string, fn_call_ph int) s
 	p.cgen.set_placeholder(fn_call_ph, '$typ $tmp = ')
 	typ = typ[7..]
 	p.genln(';')
+	or_tok_idx := p.token_idx
 	p.check(.key_orelse)
 	p.check(.lcbr)
 	p.register_var(Var {
@@ -107,15 +114,26 @@ fn (p mut Parser) gen_handle_option_or_else(_typ, name string, fn_call_ph int) s
 		is_mut: false
 		is_used: true
 	})
+	if is_assign {
+		p.genln('$typ $name;')
+	}
 	p.genln('if (!$tmp .ok) {')
 	p.genln('string err = $tmp . error;')
 	p.genln('int errcode = $tmp . ecode;')
-	p.statements()
-	if is_assign {
-		p.genln('$typ $name = *($typ*) $tmp . data;')
+	last_ph := p.cgen.add_placeholder()
+	last_typ := p.statements()
+	if is_assign && last_typ == typ {
+		expr_line := p.cgen.lines[p.cgen.lines.len-3]
+		last_expr := expr_line[last_ph..]
+		p.cgen.lines[p.cgen.lines.len-3]  = ''
+		p.genln('if (!$tmp .ok) {')
+		p.genln('$name = $last_expr;')
+		p.genln('}')
+	} else if is_assign {
+		p.genln('$name = *($typ*) $tmp . data;')
 	}
-	if !p.returns && p.prev_tok2 != .key_continue && p.prev_tok2 != .key_break {
-		p.error('`or` block must return/exit/continue/break/panic')
+	if !p.returns && last_typ != typ && is_assign && p.prev_tok2 != .key_continue && p.prev_tok2 != .key_break {
+		p.error_with_token_index('`or` block must provide a default value or return/exit/continue/break/panic', or_tok_idx)
 	}
 	p.returns = false
 	return typ
diff --git a/vlib/compiler/parser.v b/vlib/compiler/parser.v
index b38b523371..fc1ef7d2b7 100644
--- a/vlib/compiler/parser.v
+++ b/vlib/compiler/parser.v
@@ -45,6 +45,7 @@ mut:
 	inside_return_expr bool
 	inside_unsafe bool
 	is_struct_init bool
+	is_var_decl    bool
 	if_expr_cnt    int
 	for_expr_cnt   int // to detect whether `continue` can be used
 	ptr_cast       bool
@@ -1700,6 +1701,7 @@ fn (p mut Parser) name_expr() string {
 		// p.error('`$f.name` used as value')
 	}
 
+	fn_call_ph := p.cgen.add_placeholder()
 	// println('call to fn $f.name of type $f.typ')
 	// TODO replace the following dirty hacks (needs ptr access to fn table)
 	new_f := f
@@ -1713,6 +1715,17 @@ fn (p mut Parser) name_expr() string {
 	}
 	f = new_f
 
+	// optional function call `function() or {}`, no return assignment
+    is_or_else := p.tok == .key_orelse
+    if !p.is_var_decl && is_or_else {
+		f.typ = p.gen_handle_option_or_else(f.typ, '', fn_call_ph)
+	}
+    else if !p.is_var_decl && !is_or_else && !p.inside_return_expr &&
+		f.typ.starts_with('Option_') {
+        opt_type := f.typ[7..]
+        p.error('unhandled option type: `?$opt_type`')
+    }
+
 	// dot after a function call: `get_user().age`
 	if p.tok == .dot {
 		mut typ := ''
@@ -2049,11 +2062,21 @@ struct $typ.name {
 		return field.typ
 	}
 	// method
-	method := p.table.find_method(typ, field_name) or {
+	mut method := p.table.find_method(typ, field_name) or {
 		p.error_with_token_index('could not find method `$field_name`', fname_tidx) // should never happen
 		exit(1)
 	}
 	p.fn_call(mut method, method_ph, '', str_typ)
+    // optional method call `a.method() or {}`, no return assignment
+    is_or_else := p.tok == .key_orelse
+	if !p.is_var_decl && is_or_else {
+		method.typ = p.gen_handle_option_or_else(method.typ, '', method_ph)
+	}
+    else if !p.is_var_decl && !is_or_else && !p.inside_return_expr &&
+		method.typ.starts_with('Option_') {
+        opt_type := method.typ[7..]
+        p.error('unhandled option type: `?$opt_type`')
+    }
 	// Methods returning `array` should return `array_string` etc
 	if method.typ == 'array' && typ.name.starts_with('array_') {
 		return typ.name
@@ -3098,7 +3121,9 @@ fn (p mut Parser) if_st(is_expr bool, elif_depth int) string {
 		var_name := p.lit
 		p.next()
 		p.check(.decl_assign)
+		p.is_var_decl = true
 		option_type, expr := p.tmp_expr()// := p.bool_expression()
+		p.is_var_decl = false
 		typ := option_type[7..]
 		// Option_User tmp = get_user(1);
 		// if (tmp.ok) {
diff --git a/vlib/compiler/tests/defer_test.v b/vlib/compiler/tests/defer_test.v
index 88957fa5cd..c2e71900d3 100644
--- a/vlib/compiler/tests/defer_test.v
+++ b/vlib/compiler/tests/defer_test.v
@@ -46,6 +46,8 @@ fn test_defer_early_exit() {
 
 fn test_defer_option() {
 	mut ok := Num{0}
-	set_num_opt(mut ok)
+	set_num_opt(mut ok) or {
+		assert false
+	}
 	assert ok.val == 1
 }
diff --git a/vlib/compiler/tests/option_test.v b/vlib/compiler/tests/option_test.v
index a661fbe369..f9250ad38a 100644
--- a/vlib/compiler/tests/option_test.v
+++ b/vlib/compiler/tests/option_test.v
@@ -58,3 +58,15 @@ fn test_if_opt() {
 	assert 1 == 1
 	println('nice')
 }
+
+fn for_opt_default() ?string {
+        return error('awww')
+}
+
+fn test_opt_default() {
+	a := for_opt_default() or {
+			// panic(err)
+			'default'
+	}
+	assert a == 'default'
+}
diff --git a/vlib/crypto/md5/md5.v b/vlib/crypto/md5/md5.v
index 140d33def3..ce4c533e25 100644
--- a/vlib/crypto/md5/md5.v
+++ b/vlib/crypto/md5/md5.v
@@ -55,7 +55,7 @@ pub fn new() &Digest {
 	return d
 }
 
-pub fn (d mut Digest) write(p_ []byte) ?int {
+pub fn (d mut Digest) write(p_ []byte) int {
 	mut p := p_
 	nn := p.len
 	d.len += u64(nn)
diff --git a/vlib/crypto/sha1/sha1.v b/vlib/crypto/sha1/sha1.v
index 0ee34864a5..ca96b4891f 100644
--- a/vlib/crypto/sha1/sha1.v
+++ b/vlib/crypto/sha1/sha1.v
@@ -58,7 +58,7 @@ pub fn new() &Digest {
 	return d
 }
 
-pub fn (d mut Digest) write(p_ []byte) ?int {
+pub fn (d mut Digest) write(p_ []byte) int {
 	mut p := p_
 	nn := p.len
 	d.len += u64(nn)
diff --git a/vlib/crypto/sha256/sha256.v b/vlib/crypto/sha256/sha256.v
index 9753555e87..0126973682 100644
--- a/vlib/crypto/sha256/sha256.v
+++ b/vlib/crypto/sha256/sha256.v
@@ -92,7 +92,7 @@ pub fn new224() &Digest {
 	return d
 }
 
-fn (d mut Digest) write(p_ []byte) ?int {
+fn (d mut Digest) write(p_ []byte) int {
 	mut p := p_
 	nn := p.len
 	d.len += u64(nn)
diff --git a/vlib/crypto/sha512/sha512.v b/vlib/crypto/sha512/sha512.v
index d5fcd11d2b..b804286d99 100644
--- a/vlib/crypto/sha512/sha512.v
+++ b/vlib/crypto/sha512/sha512.v
@@ -151,7 +151,7 @@ fn new384() &Digest {
 	return new_digest(.sha384)
 }
 
-fn (d mut Digest) write(p_ []byte) ?int {
+fn (d mut Digest) write(p_ []byte) int {
 	mut p := p_
 	nn := p.len
 	d.len += u64(nn)
diff --git a/vlib/encoding/csv/csv_test.v b/vlib/encoding/csv/csv_test.v
index 08e7c80539..b859d7b4e9 100644
--- a/vlib/encoding/csv/csv_test.v
+++ b/vlib/encoding/csv/csv_test.v
@@ -32,9 +32,9 @@ fn test_encoding_csv_reader() {
 fn test_encoding_csv_writer() {
 	mut csv_writer := csv.new_writer()
 
-	csv_writer.write(['name', 'email', 'phone', 'other'])
-	csv_writer.write(['joe', 'joe@blow.com', '0400000000', 'test'])
-	csv_writer.write(['sam', 'sam@likesham.com', '0433000000', 'needs, quoting'])
+	csv_writer.write(['name', 'email', 'phone', 'other']) or {}
+	csv_writer.write(['joe', 'joe@blow.com', '0400000000', 'test']) or {}
+	csv_writer.write(['sam', 'sam@likesham.com', '0433000000', 'needs, quoting']) or {}
 
 	assert csv_writer.str() == 'name,email,phone,other\njoe,joe@blow.com,0400000000,test\nsam,sam@likesham.com,0433000000,"needs, quoting"\n'
 }
diff --git a/vlib/http/http_client.v b/vlib/http/http_client.v
index 1d04a7013f..0fd701c77a 100644
--- a/vlib/http/http_client.v
+++ b/vlib/http/http_client.v
@@ -10,13 +10,13 @@ fn (req &Request) http_do(port int, method, host_name, path string) ?Response {
 	s := req.build_request_headers(method, host_name, path)
 	
 	client := net.dial( host_name, port) or { return error(err) }
-	client.send( s.str, s.len )
+	client.send( s.str, s.len ) or {}
 	for {
 		readbytes := client.crecv( rbuffer, bufsize )
 		if readbytes  < 0 { return error('http_do error reading response. readbytes: $readbytes') }
 		if readbytes == 0 { break }
 		sb.write( tos(rbuffer, readbytes) )
 	}
-	client.close()	
+	client.close() or {}
 	return parse_response(sb.str())
 }
diff --git a/vlib/net/socket_test.v b/vlib/net/socket_test.v
index e72b8d28f6..a98b31ad3d 100644
--- a/vlib/net/socket_test.v
+++ b/vlib/net/socket_test.v
@@ -13,7 +13,9 @@ fn test_socket() {
 	}
 	
 	message := 'Hello World'
-	socket.send(message.str, message.len)	
+	socket.send(message.str, message.len) or {
+		assert false
+	}
 	$if debug {	println('message send: $message')	}
 	$if debug {	println('send socket: $socket.sockfd')	}
 
@@ -24,7 +26,7 @@ fn test_socket() {
 
 	assert message == received
 
-	server.close()
-	client.close()
-	socket.close()
+	server.close() or {}
+	client.close() or {}
+	socket.close() or {}
 }
diff --git a/vlib/net/urllib/urllib.v b/vlib/net/urllib/urllib.v
index 1909a40653..55de2d4f62 100644
--- a/vlib/net/urllib/urllib.v
+++ b/vlib/net/urllib/urllib.v
@@ -537,7 +537,7 @@ fn parse_url(rawurl string, via_request bool) ?URL {
 	// raw_path is a hint of the encoding of path. We don't want to set it if
 	// the default escaping of path is equivalent, to help make sure that people
 	// don't rely on it in general.
-	_ = url.set_path(rest) or {
+	url.set_path(rest) or {
 		return error(err)
 	}
 	return url
@@ -974,7 +974,7 @@ pub fn (u &URL) resolve_reference(ref &URL) ?URL {
 		// The 'absoluteURI' or 'net_path' cases.
 		// We can ignore the error from set_path since we know we provided a
 		// validly-escaped path.
-		url.set_path(resolve_path(ref.escaped_path(), ''))
+		url.set_path(resolve_path(ref.escaped_path(), '')) or {return error(err)}
 		return url
 	}
 	if ref.opaque != '' {
@@ -992,7 +992,7 @@ pub fn (u &URL) resolve_reference(ref &URL) ?URL {
 	// The 'abs_path' or 'rel_path' cases.
 	url.host = u.host
 	url.user = u.user
-	url.set_path(resolve_path(u.escaped_path(), ref.escaped_path()))
+	url.set_path(resolve_path(u.escaped_path(), ref.escaped_path())) or { return error(err) }
 	return url
 }
 
diff --git a/vlib/sqlite/sqlite_test.v b/vlib/sqlite/sqlite_test.v
index e3918f76d3..0ee541e99e 100644
--- a/vlib/sqlite/sqlite_test.v
+++ b/vlib/sqlite/sqlite_test.v
@@ -2,6 +2,7 @@ import sqlite
 
 fn test_sqlite() {
 	db := sqlite.connect('users.db')
+	db.exec("drop table if exists users")
 	db.exec("create table users (id integer primary key, name text default '');")
 	
 	db.exec("insert into users (name) values ('Sam')")