all: update chdir usages

cmd/tools/modules/testing/common.v

@@ -444,7 +444,7 @@ pub fn building_any_v_binaries_failed() bool {
 	vexe := pref.vexe_path()
 	parent_dir := os.dir(vexe)
 	vlib_should_be_present(parent_dir)
-	os.chdir(parent_dir)
+	os.chdir(parent_dir) or { panic(err) }
 	mut failed := false
 	v_build_commands := ['$vexe -o v_g             -g  cmd/v', '$vexe -o v_prod_g  -prod -g  cmd/v',
 		'$vexe -o v_cg            -cg cmd/v', '$vexe -o v_prod_cg -prod -cg cmd/v',

cmd/tools/vtest-self.v

@@ -133,7 +133,7 @@ const (
 fn main() {
 	vexe := pref.vexe_path()
 	vroot := os.dir(vexe)
-	os.chdir(vroot)
+	os.chdir(vroot) or { panic(err) }
 	args := os.args.clone()
 	args_string := args[1..].join(' ')
 	cmd_prefix := args_string.all_before('test-self')

vlib/flag/default_flag_options_test.v

@@ -5,7 +5,7 @@ const source = 'vlib/flag/testdata/simplest_flag_program.v'
 const simple_flag_app_executable = os.real_path(os.join_path(os.cache_dir(), 'simple_flag_app.exe'))
 
 fn testsuite_begin() {
-	os.chdir(@VMODROOT)
+	os.chdir(@VMODROOT) or {}
 	os.rm(simple_flag_app_executable) or {}
 	res := os.execute('${@VEXE} -o $simple_flag_app_executable $source')
 	assert res.exit_code == 0

vlib/flag/usage_example_test.v

@@ -5,7 +5,7 @@ const the_source = 'vlib/flag/testdata/usage_example.v'
 const the_executable = os.real_path(os.join_path(os.cache_dir(), 'flag_usage_example_app.exe'))
 
 fn testsuite_begin() {
-	os.chdir(@VMODROOT)
+	os.chdir(@VMODROOT) or {}
 	os.rm(the_executable) or {}
 	res := os.execute('${@VEXE} -o $the_executable $the_source')
 	assert res.exit_code == 0