(fix) defensively call ts function

dummdidumm · web-flow · commit 9f287a3fef3a · 2020-11-23T18:18:12.000+01:00
It got added only recently (TS 4.0) and might break people using older TS versions in context of `svelte-check` #685
diff --git a/packages/svelte2tsx/src/svelte2tsx/processInstanceScriptContent.ts b/packages/svelte2tsx/src/svelte2tsx/processInstanceScriptContent.ts
@@ -448,7 +448,9 @@ export function processInstanceScriptContent(
             }
         }
 
-        if (ts.isTypeAssertionExpression(node)) {
+        // Defensively call function (checking for undefined) because it got added only recently (TS 4.0)
+        // and therefore might break people using older TS versions
+        if (ts.isTypeAssertionExpression?.(node)) {
             handleTypeAssertion(str, node, astOffset);
         }
 

Original file line number	Diff line number	Diff line change
`@@ -448,7 +448,9 @@ export function processInstanceScriptContent(`
`448`	`448`	`}`
`449`	`449`	`}`
`450`	`450`
`451`		`- if (ts.isTypeAssertionExpression(node)) {`
	`451`	`+ // Defensively call function (checking for undefined) because it got added only recently (TS 4.0)`
	`452`	`+ // and therefore might break people using older TS versions`
	`453`	`+ if (ts.isTypeAssertionExpression?.(node)) {`
`452`	`454`	`handleTypeAssertion(str, node, astOffset);`
`453`	`455`	`}`
`454`	`456`