make flow happy

.flowconfig

 [ignore]
 
+# We fork some components by platform.
+.*/*[.]android.js
+
+# Ignore templates with `@flow` in header
+.*/local-cli/generator.*
+
+# Ignore malformed json
+.*/node_modules/y18n/test/.*\.json
+
+# Ignore unexpected extra @providesModule
+.*/node_modules/commoner/test/source/widget/share.js
+
+# Ignore duplicate module providers
+# For RN Apps installed via npm, "Libraries" folder is inside node_modules/react-native but in the source repo it is in the root
+.*/Libraries/react-native/React.js
+.*/Libraries/react-native/ReactNative.js
+.*/node_modules/jest-runtime/build/__tests__/.*
+
 [include]
 
 [libs]
+node_modules/react-native/Libraries/react-native/react-native-interface.js
+node_modules/react-native/flow
+flow/
 
 [options]
+module.system=haste
+
+esproposal.class_static_fields=enable
+esproposal.class_instance_fields=enable
+
+experimental.strict_type_args=true
+
+munge_underscores=true
+
+module.name_mapper='^image![a-zA-Z0-9$_-]+$' -> 'GlobalImageStub'
+module.name_mapper='^[./a-zA-Z0-9$_-]+\.\(bmp\|gif\|jpg\|jpeg\|png\|psd\|svg\|webp\|m4v\|mov\|mp4\|mpeg\|mpg\|webm\|aac\|aiff\|caf\|m4a\|mp3\|wav\|html\|pdf\)$' -> 'RelativeImageStub'
+
+suppress_type=$FlowIssue
+suppress_type=$FlowFixMe
+suppress_type=$FixMe
+
+suppress_comment=\\(.\\|\n\\)*\\$FlowFixMe\\($\\|[^(]\\|(\\(>=0\\.\\(3[0-2]\\|[1-2][0-9]\\|[0-9]\\).[0-9]\\)? *\\(site=[a-z,_]*react_native[a-z,_]*\\)?)\\)
+suppress_comment=\\(.\\|\n\\)*\\$FlowIssue\\((\\(>=0\\.\\(3[0-2]\\|1[0-9]\\|[1-2][0-9]\\).[0-9]\\)? *\\(site=[a-z,_]*react_native[a-z,_]*\\)?)\\)?:? #[0-9]+
+suppress_comment=\\(.\\|\n\\)*\\$FlowFixedInNextDeploy
+
+unsafe.enable_getters_and_setters=true

index.js

   }
 ): Promise<string> {
   if (typeof view !== "number") {
-    view = findNodeHandle(view);
+    const node = findNodeHandle(view);
+    if (!node) return Promise.reject(new Error("findNodeHandle failed to resolve view="+String(view)));
+    view = node;
   }
   return RNViewShot.takeSnapshot(view, options);
 }