Avoid invalid code when "else" branch is simplified (#3421)

* Make sure there is always whitespace between "else" and the subsequent statement to avoid invalid code when the alternate branch is simplified.

* Fix comment

src/ast/nodes/IfStatement.ts

@@ -82,6 +82,9 @@ export default class IfStatement extends StatementBase implements DeoptimizableE
 			}
 			if (this.alternate !== null) {
 				if (this.alternate.included) {
+					if (code.original.charCodeAt(this.alternate.start - 1) === 101 /* e */) {
+						code.prependLeft(this.alternate.start, ' ');
+					}
 					this.alternate.render(code, options);
 				} else {
 					code.remove(this.consequent.end, this.alternate.end);

test/function/samples/if-statement-insert-whitespace/_config.js

@@ -0,0 +1,11 @@
+module.exports = {
+	description: 'inserts necessary white-space when simplifying if-statements (#3419)',
+	options: {
+		external: 'external'
+	},
+	context: {
+		require(required) {
+			return false;
+		}
+	}
+};

test/function/samples/if-statement-insert-whitespace/main.js

@@ -0,0 +1,8 @@
+let works = false;
+const makeItWork = () => works = true;
+
+import value from 'external';
+
+if (value) {} else"production"!=="local"?makeItWork():void 0;
+
+assert.ok(works);