fix(migrations): Fix cf migration let condition semicolon order (#56913)

In rare cases people may put let statements before else statements and omit semicolons, causing migration issues.

PR Close #56913

packages/core/schematics/ng-generate/control-flow-migration/types.ts

@@ -150,8 +150,19 @@ export class ElementToMigrate {
     this.aliasAttrs = aliasAttrs;
   }
 
+  normalizeConditionString(value: string): string {
+    value = this.insertSemicolon(value, value.indexOf(' else '));
+    value = this.insertSemicolon(value, value.indexOf(' then '));
+    value = this.insertSemicolon(value, value.indexOf(' let '));
+    return value.replace(';;', ';');
+  }
+
+  insertSemicolon(str: string, ix: number): string {
+    return ix > -1 ? `${str.slice(0, ix)};${str.slice(ix)}` : str;
+  }
+
   getCondition(): string {
-    const chunks = this.attr.value.split(';');
+    const chunks = this.normalizeConditionString(this.attr.value).split(';');
     let condition = chunks[0];
 
     // checks for case of no usage of `;` in if else / if then else

packages/core/schematics/test/control_flow_migration_spec.ts

@@ -1674,6 +1674,48 @@ describe('control flow migration', () => {
       );
     });
 
+    it('should migrate if/else with let variable in wrong place with no semicolons', async () => {
+      writeFile(
+        '/comp.ts',
+        `
+        import {Component} from '@angular/core';
+        import {NgIf} from '@angular/common';
+
+        @Component({
+          templateUrl: './comp.html'
+        })
+        class Comp {
+          user$ = of({ name: 'Jane' }})
+        }
+      `,
+      );
+
+      writeFile(
+        '/comp.html',
+        [
+          `<div>`,
+          `<div *ngIf="user of users; let tooltipContent else noUserBlock">{{ user.name }}</div>`,
+          `<ng-template #noUserBlock>No user</ng-template>`,
+          `</div>`,
+        ].join('\n'),
+      );
+
+      await runMigration();
+      const content = tree.readContent('/comp.html');
+
+      expect(content).toBe(
+        [
+          `<div>`,
+          `  @if (user of users; as tooltipContent) {`,
+          `    <div>{{ user.name }}</div>`,
+          `  } @else {`,
+          `    No user`,
+          `  }`,
+          `</div>`,
+        ].join('\n'),
+      );
+    });
+
     it('should migrate if/then/else with alias', async () => {
       writeFile(
         '/comp.ts',