fix(FileMaker Node): Prevent erroring on zero fields loaded (#7955)

## Summary
https://n8nio.sentry.io/issues/4703111361

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packages/nodes-base/nodes/FileMaker/FileMaker.node.ts

@@ -625,6 +625,8 @@ export class FileMaker implements INodeType {
 
 				const fields = await getFields.call(this);
 
+				if (!Array.isArray(fields)) return [];
+
 				for (const field of fields) {
 					returnData.push({
 						name: field.name,