cgen: fix error for if cond with optional expr (#14334)

vlib/v/gen/c/cgen.v

@@ -5133,9 +5133,7 @@ fn (mut g Gen) or_block(var_name string, or_block ast.OrExpr, return_type ast.Ty
 					g.inside_opt_data = true
 					g.expr_with_cast(expr_stmt.expr, expr_stmt.typ, return_type.clear_flag(.optional))
 					g.inside_opt_data = old_inside_opt_data
-					if g.inside_ternary == 0 {
+					g.writeln(';')
-						g.writeln(';')
-					}
 					g.stmt_path_pos.delete_last()
 				} else {
 					g.stmt(stmt)

vlib/v/tests/if_cond_with_optional_test.v

@@ -0,0 +1,43 @@
+module main
+
+import rand
+
+interface Sample {
+mut:
+	get_next() int
+}
+
+struct SampleA {
+mut:
+	state int
+}
+
+fn (mut sample SampleA) get_next() int {
+	sample.state++
+	return sample.state
+}
+
+struct SampleB {
+mut:
+	state int = 1
+}
+
+fn (mut sample SampleB) get_next() int {
+	sample.state += 2
+	return sample.state
+}
+
+fn create_sampler() Sample {
+	return if rand.intn(1) or { 0 } == 0 { Sample(SampleA{}) } else { Sample(SampleB{}) }
+}
+
+fn test_if_cond_with_optional() {
+	mut sample := create_sampler()
+	mut ret := sample.get_next()
+	println(ret)
+	assert ret == 1
+
+	ret = sample.get_next()
+	println(ret)
+	assert ret == 2
+}