3 files changed, 52 insertions, 2 deletions
diff --git a/packages/instant/src/util/assert.ts b/packages/instant/src/util/assert.ts
new file mode 100644
index 000000000..584d3d4b1
--- /dev/null
+++ b/packages/instant/src/util/assert.ts
@@ -0,0 +1,44 @@
+import { assert as sharedAssert } from '@0x/assert';
+import { schemas } from '@0x/json-schemas';
+import { assetDataUtils } from '@0x/order-utils';
+import { AssetProxyId, ObjectMap, SignedOrder } from '@0x/types';
+import * as _ from 'lodash';
+
+import { AssetMetaData } from '../types';
+
+export const assert = {
+    ...sharedAssert,
+    isValidLiquiditySource(variableName: string, liquiditySource: string | SignedOrder[]): void {
+        if (_.isString(liquiditySource)) {
+            sharedAssert.isUri(variableName, liquiditySource);
+            return;
+        }
+        sharedAssert.doesConformToSchema(variableName, liquiditySource, schemas.signedOrdersSchema);
+    },
+    isValidAssetMetaDataMap(variableName: string, metaDataMap: ObjectMap<AssetMetaData>): void {
+        _.forEach(metaDataMap, (metaData, assetData) => {
+            assert.isHexString(`key ${assetData} of ${variableName}`, assetData);
+            assert.isValidAssetMetaData(`${variableName}.${assetData}`, metaData);
+            const assetDataProxyId = assetDataUtils.decodeAssetProxyId(assetData);
+            assert.assert(
+                metaData.assetProxyId === assetDataProxyId,
+                `Expected meta data for assetData ${assetData} to have asset proxy id of ${assetDataProxyId}, but instead got ${
+                    metaData.assetProxyId
+                }`,
+            );
+        });
+    },
+    isValidAssetMetaData(variableName: string, metaData: AssetMetaData): void {
+        assert.isHexString(`${variableName}.assetProxyId`, metaData.assetProxyId);
+        if (!_.isUndefined(metaData.primaryColor)) {
+            assert.isString(`${variableName}.primaryColor`, metaData.primaryColor);
+        }
+        if (metaData.assetProxyId === AssetProxyId.ERC20) {
+            assert.isNumber(`${variableName}.decimals`, metaData.decimals);
+            assert.isString(`${variableName}.symbol`, metaData.symbol);
+        } else if (metaData.assetProxyId === AssetProxyId.ERC721) {
+            assert.isString(`${variableName}.name`, metaData.name);
+            assert.isUri(`${variableName}.imageUrl`, metaData.imageUrl);
+        }
+    },
+};
diff --git a/packages/instant/src/util/asset.ts b/packages/instant/src/util/asset.ts
index 2c5b6325d..630103c7b 100644
--- a/packages/instant/src/util/asset.ts
+++ b/packages/instant/src/util/asset.ts
@@ -18,7 +18,10 @@ export const assetUtils = {
     getMetaDataOrThrow: (assetData: string, metaDataMap: ObjectMap<AssetMetaData>, network: Network): AssetMetaData => {
         let mainnetAssetData: string | undefined = assetData;
         if (network !== Network.Mainnet) {
-            mainnetAssetData = assetUtils.getAssociatedAssetDataIfExists(assetData, network);
+            const mainnetAssetDataIfExists = assetUtils.getAssociatedAssetDataIfExists(assetData, network);
+            // Just so we don't fail in the case where we are on a non-mainnet network,
+            // but pass in a valid mainnet assetData.
+            mainnetAssetData = mainnetAssetDataIfExists || assetData;
         }
         if (_.isUndefined(mainnetAssetData)) {
             throw new Error(ZeroExInstantError.AssetMetaDataNotAvailable);
diff --git a/packages/instant/src/util/error.ts b/packages/instant/src/util/error.ts
index 64c1f4885..844a28d8b 100644
--- a/packages/instant/src/util/error.ts
+++ b/packages/instant/src/util/error.ts
@@ -1,4 +1,5 @@
 import { AssetBuyerError } from '@0x/asset-buyer';
+import * as _ from 'lodash';
 import { Dispatch } from 'redux';
 
 import { Action, actions } from '../redux/actions';
@@ -10,7 +11,6 @@ class ErrorFlasher {
     private _timeoutId?: number;
     public flashNewError(dispatch: Dispatch<Action>, error: any, delayMs: number = 7000): void {
         this._clearTimeout();
-
         // dispatch new message
         dispatch(actions.setError(error));
 
@@ -60,6 +60,9 @@ export const errorUtil = {
         if (error instanceof Error) {
             bestMessage = humanReadableMessageForError(error, asset);
         }
+        if (_.isString(error)) {
+            bestMessage = error;
+        }
         return {
             icon: '😢',
             message: bestMessage || 'Something went wrong...',