fix: Fixes issue on values being undefined on initial is collapsed check (#87)

Author: reinhard-sanz

.changeset/twelve-stingrays-greet.md

@@ -0,0 +1,5 @@
+---
+"paneforge": patch
+---
+
+fix: Fixes issue on values being undefined on initial is collapsed check

packages/paneforge/src/lib/paneforge.svelte.ts

@@ -336,6 +336,9 @@ export class PaneGroupState {
 			paneSize,
 		} = paneDataHelper(paneDataArray, pane, layout);
 
+		// On init the value may be undefined, so we need to check for that
+		if (typeof paneSize !== "number" || typeof collapsedSize !== "number") return false;
+
 		return collapsible === true && areNumbersAlmostEqual(paneSize, collapsedSize);
 	};