Spawn handler: wrap the program call with try/catch, exit gracefully …

…on error (#1320)

Prevents unhandled rejections when the spawned program crashes.

## Testing Instructions

Confirm CI tests pass

packages/php-wasm/util/src/lib/create-spawn-handler.spec.ts

@@ -35,4 +35,25 @@ describe('createSpawnHandler', () => {
 			});
 		});
 	});
+
+	it('should exit with code 1 when the spawned process throws an exception', async () => {
+		const command = 'testCommand';
+		const program = vitest.fn(() => {
+			throw new Error('Program crash');
+		});
+
+		const spawnHandler = createSpawnHandler(program);
+		const childProcess = spawnHandler(command);
+
+		const errorfn = vitest.fn();
+		await new Promise((done) => {
+			childProcess.on('error', errorfn);
+			childProcess.on('exit', (code: number) => {
+				expect(code).toBe(1);
+				expect(program).toHaveBeenCalled();
+				done(null);
+			});
+		});
+		expect(errorfn).toHaveBeenCalledWith(new Error('Program crash'));
+	});
 });

packages/php-wasm/util/src/lib/create-spawn-handler.ts

@@ -47,7 +47,20 @@ export function createSpawnHandler(
 			} else {
 				throw new Error('Invalid command ', command);
 			}
-			await program(commandArray, processApi, options);
+			try {
+				await program(commandArray, processApi, options);
+			} catch (e) {
+				childProcess.emit('error', e);
+				if (
+					typeof e === 'object' &&
+					e !== null &&
+					'message' in e &&
+					typeof e.message === 'string'
+				) {
+					processApi.stderr(e.message);
+				}
+				processApi.exit(1);
+			}
 			childProcess.emit('spawn', true);
 		});
 		return childProcess;