Remove unhelpful and slightly buggy enhanceErrorWithDocument function.

Extending the built-in `Error` class in TypeScript results in a subclass
whose `.prototype` is simply `Error.prototype`, rather than (in this case)
`WriteError.prototype`, so this code never worked as intended, because
`new WriteError(message) instanceof WriteError` would never be true.

Relevant discussion (content warning: maintainers refusing to fix
deviations from the ECMAScript specification for reasons that are not even
remotely compelling): microsoft/TypeScript#12123
microsoft/TypeScript#12581

More subjectively (IMHO), the additional messaging did not ease debugging
enough to justify its contribution to bundle sizes.

Author: benjamn

src/cache/inmemory/__tests__/__snapshots__/roundtrip.ts.snap

@@ -1,7 +1,3 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`writing to the store throws when trying to write an object without id that was previously queried with id 1`] = `
-"Error writing result to store for query:
- {\\"kind\\":\\"Document\\",\\"definitions\\":[{\\"kind\\":\\"OperationDefinition\\",\\"operation\\":\\"query\\",\\"name\\":{\\"kind\\":\\"Name\\",\\"value\\":\\"Failure\\"},\\"variableDefinitions\\":[],\\"directives\\":[],\\"selectionSet\\":{\\"kind\\":\\"SelectionSet\\",\\"selections\\":[{\\"kind\\":\\"Field\\",\\"name\\":{\\"kind\\":\\"Name\\",\\"value\\":\\"item\\"},\\"arguments\\":[],\\"directives\\":[],\\"selectionSet\\":{\\"kind\\":\\"SelectionSet\\",\\"selections\\":[{\\"kind\\":\\"Field\\",\\"name\\":{\\"kind\\":\\"Name\\",\\"value\\":\\"stringField\\"},\\"arguments\\":[],\\"directives\\":[]}]}}]}}],\\"loc\\":{\\"start\\":0,\\"end\\":106}}
-Store error: the application attempted to write an object with no provided id but the store already contains an id of abcd for this object."
-`;
+exports[`writing to the store throws when trying to write an object without id that was previously queried with id 1`] = `"Store error: the application attempted to write an object with no provided id but the store already contains an id of abcd for this object."`;

src/cache/inmemory/__tests__/__snapshots__/writeToStore.ts.snap

@@ -1,7 +1,3 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`writing to the store throws when trying to write an object without id that was previously queried with id 1`] = `
-"Error writing result to store for query:
- {\\"kind\\":\\"Document\\",\\"definitions\\":[{\\"kind\\":\\"OperationDefinition\\",\\"operation\\":\\"query\\",\\"name\\":{\\"kind\\":\\"Name\\",\\"value\\":\\"Failure\\"},\\"variableDefinitions\\":[],\\"directives\\":[],\\"selectionSet\\":{\\"kind\\":\\"SelectionSet\\",\\"selections\\":[{\\"kind\\":\\"Field\\",\\"name\\":{\\"kind\\":\\"Name\\",\\"value\\":\\"item\\"},\\"arguments\\":[],\\"directives\\":[],\\"selectionSet\\":{\\"kind\\":\\"SelectionSet\\",\\"selections\\":[{\\"kind\\":\\"Field\\",\\"name\\":{\\"kind\\":\\"Name\\",\\"value\\":\\"stringField\\"},\\"arguments\\":[],\\"directives\\":[]}]}}]}}],\\"loc\\":{\\"start\\":0,\\"end\\":106}}
-Store error: the application attempted to write an object with no provided id but the store already contains an id of abcd for this object."
-`;
+exports[`writing to the store throws when trying to write an object without id that was previously queried with id 1`] = `"Store error: the application attempted to write an object with no provided id but the store already contains an id of abcd for this object."`;

src/cache/inmemory/__tests__/writeToStore.ts

@@ -1660,7 +1660,7 @@ describe('writing to the store', () => {
         },
         dataIdFromObject: getIdField,
       });
-    }).toThrowError(/stringField(.|\n)*abcd/g);
+    }).toThrowError(/contains an id of abcd/g);
   });
 
   it('properly handles the connection directive', () => {

src/cache/inmemory/writeToStore.ts

@@ -27,20 +27,6 @@ import {
 } from './helpers';
 import { defaultDataIdFromObject } from './inMemoryCache';
 
-export class WriteError extends Error {
-  public type = 'WriteError';
-}
-
-export function enhanceErrorWithDocument(error: Error, document: DocumentNode) {
-  // XXX A bit hacky maybe ...
-  const enhancedError = new WriteError(
-    `Error writing result to store for query:\n ${JSON.stringify(document)}`,
-  );
-  enhancedError.message += '\n' + error.message;
-  enhancedError.stack = error.stack;
-  return enhancedError;
-}
-
 export type WriteContext = {
   readonly store: NormalizedCache;
   readonly processedData: { [x: string]: Set<FieldNode> };
@@ -90,25 +76,21 @@ export class StoreWriter {
     dataIdFromObject?: IdGetter;
   }): NormalizedCache {
     const operationDefinition = getOperationDefinition(query)!;
-    try {
-      return this.writeSelectionSetToStore({
-        result,
-        dataId,
-        selectionSet: operationDefinition.selectionSet,
-        context: {
-          store,
-          processedData: {},
-          variables: {
-            ...getDefaultValues(operationDefinition),
-            ...variables,
-          },
-          dataIdFromObject,
-          fragmentMap: createFragmentMap(getFragmentDefinitions(query)),
+    return this.writeSelectionSetToStore({
+      result,
+      dataId,
+      selectionSet: operationDefinition.selectionSet,
+      context: {
+        store,
+        processedData: {},
+        variables: {
+          ...getDefaultValues(operationDefinition),
+          ...variables,
         },
-      });
-    } catch (e) {
-      throw enhanceErrorWithDocument(e, query);
-    }
+        dataIdFromObject,
+        fragmentMap: createFragmentMap(getFragmentDefinitions(query)),
+      },
+    });
   }
 
   public writeSelectionSetToStore({