Patch for GitHub issue 5.

Author: billmalarky

lib/imageCacheHoc.js

@@ -159,7 +159,11 @@ export default function imageCacheHoc(Image, options = {}) {
     async componentWillUnmount() {
 
       // Cancel pending setState() actions.
-      this.cancelLocalFilePathRequest();
+      // NOTE: must check this.cancelLocalFilePathRequest is set to avoid edge case where component is mounted then immediately unmounted before componentDidMount() fires.
+      if (this.cancelLocalFilePathRequest) {
+        this.cancelLocalFilePathRequest();
+      }
+
 
       // Remove component cache lock on associated image file on component teardown.
       let fileName = await this.fileSystem.getFileNameFromUrl(traverse(this.props).get(['source', 'uri']));