fix: Fix bug in IF block generators. (#8780)

Author: michaela-mm

generators/dart/logic.ts

@@ -46,7 +46,9 @@ export function controls_if(block: Block, generator: DartGenerator) {
   } while (block.getInput('IF' + n));
 
   if (block.getInput('ELSE') || generator.STATEMENT_SUFFIX) {
-    branchCode = generator.statementToCode(block, 'ELSE');
+    branchCode = block.getInput('ELSE')
+      ? generator.statementToCode(block, 'ELSE')
+      : '';
     if (generator.STATEMENT_SUFFIX) {
       branchCode =
         generator.prefixLines(

generators/javascript/logic.ts

@@ -44,7 +44,9 @@ export function controls_if(block: Block, generator: JavascriptGenerator) {
   } while (block.getInput('IF' + n));
 
   if (block.getInput('ELSE') || generator.STATEMENT_SUFFIX) {
-    let branchCode = generator.statementToCode(block, 'ELSE');
+    let branchCode = block.getInput('ELSE')
+      ? generator.statementToCode(block, 'ELSE')
+      : '';
     if (generator.STATEMENT_SUFFIX) {
       branchCode =
         generator.prefixLines(

generators/lua/logic.ts

@@ -39,7 +39,9 @@ export function controls_if(block: Block, generator: LuaGenerator): string {
   } while (block.getInput('IF' + n));
 
   if (block.getInput('ELSE') || generator.STATEMENT_SUFFIX) {
-    let branchCode = generator.statementToCode(block, 'ELSE');
+    let branchCode = block.getInput('ELSE')
+      ? generator.statementToCode(block, 'ELSE')
+      : '';
     if (generator.STATEMENT_SUFFIX) {
       branchCode =
         generator.prefixLines(

generators/php/logic.ts

@@ -46,7 +46,9 @@ export function controls_if(block: Block, generator: PhpGenerator) {
   } while (block.getInput('IF' + n));
 
   if (block.getInput('ELSE') || generator.STATEMENT_SUFFIX) {
-    branchCode = generator.statementToCode(block, 'ELSE');
+    branchCode = block.getInput('ELSE')
+      ? generator.statementToCode(block, 'ELSE')
+      : '';
     if (generator.STATEMENT_SUFFIX) {
       branchCode =
         generator.prefixLines(

generators/python/logic.ts

@@ -40,7 +40,11 @@ export function controls_if(block: Block, generator: PythonGenerator) {
   } while (block.getInput('IF' + n));
 
   if (block.getInput('ELSE') || generator.STATEMENT_SUFFIX) {
-    branchCode = generator.statementToCode(block, 'ELSE') || generator.PASS;
+    if (block.getInput('ELSE')) {
+      branchCode = generator.statementToCode(block, 'ELSE') || generator.PASS;
+    } else {
+      branchCode = generator.PASS;
+    }
     if (generator.STATEMENT_SUFFIX) {
       branchCode =
         generator.prefixLines(