STRF-4889: Fix error message for upload limit

* Status code 409 is overloaded for two conditions: (1) Private theme
  count limit (2) Private theme concurrent upload limit.
* Use the error message to disambiguate and present the correct error.
  This is fragile, but all we have at the moment.

lib/theme-api-client.js

@@ -156,11 +156,20 @@ function postTheme(options, callback) {
         }
 
         if (response.statusCode === 409) {
-            return callback(null, { themeLimitReached: true });
+            // This status code is overloaded, so we need to check the message to determine
+            // if we want to trigger the theme deletion flow.
+            const uploadLimitPattern = /You have reached your upload limit/;
+            if (payload && payload.title && uploadLimitPattern.exec(payload.title)) {
+                return callback(null, { themeLimitReached: true });
+            }
+
+            const message = 'You already have a theme upload in progress. You will need to wait for it to finish processing before uploading a new one.';
+            return callback(new Error(payload && payload.title || message));
         }
 
         if (response.statusCode === 413) {
-            return callback(new Error(payload && payload.title || 'Theme Bundle Size Limit Reached'));
+            const message = 'Your theme bundle is too large. Please reduce the size of your assets to bring the zip file size under 50MB.';
+            return callback(new Error(payload && payload.title || message));
         }
 
         if (response.statusCode !== 201) {

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@bigcommerce/stencil-cli",
-  "version": "1.14.2",
+  "version": "1.14.3",
   "description": "CLI tool to run BigCommerce Stores locally for theme development.",
   "main": "index.js",
   "engines": {