Error fixes / catches

- Barcode scan returns invalid response
- model.reload() returns invalid response
- model.create() returns invalid response
- model.get() returns invalid response

lib/barcode.dart

@@ -1,4 +1,5 @@
 import 'package:inventree/app_settings.dart';
+import 'package:inventree/inventree/sentry.dart';
 import 'package:inventree/widget/dialogs.dart';
 import 'package:inventree/widget/snacks.dart';
 import 'package:audioplayers/audioplayers.dart';
@@ -98,18 +99,28 @@ class BarcodeHandler {
           expectedStatusCode: 200
       );
 
-      if (!response.isValid()) {
-        return;
-      }
-
-      if (response.data.containsKey('error')) {
       _controller?.resumeCamera();
+
+      // Handle strange response from the server
+      if (!response.isValid() || response.data == null || !(response.data is Map)) {
+        onBarcodeUnknown(context, {});
+
+        // We want to know about this one!
+        await sentryReportMessage(
+            "BarcodeHandler.processBarcode returned strange value",
+            context: {
+              "data": response.data?.toString() ?? "null",
+              "barcode": barcode,
+              "url": url,
+              "statusCode": response.statusCode.toString(),
+              "valid": response.isValid().toString(),
+            }
+        );
+      } else if (response.data.containsKey('error')) {
         onBarcodeUnknown(context, response.data);
       } else if (response.data.containsKey('success')) {
-        _controller?.resumeCamera();
         onBarcodeMatched(context, response.data);
       } else {
-        _controller?.resumeCamera();
         onBarcodeUnhandled(context, response.data);
       }
     }

lib/inventree/model.dart

@@ -2,6 +2,7 @@ import 'dart:async';
 
 import 'package:inventree/api.dart';
 import 'package:flutter/cupertino.dart';
+import 'package:inventree/inventree/sentry.dart';
 import 'package:url_launcher/url_launcher.dart';
 
 import 'package:path/path.dart' as path;
@@ -148,8 +149,21 @@ class InvenTreeModel {
 
     var response = await api.get(url, params: defaultGetFilters(), expectedStatusCode: 200);
 
-    if (!response.isValid()) {
+    if (!response.isValid() || response.data == null || !(response.data is Map)) {
+
+      // Report error
+      await sentryReportMessage(
+        "InvenTreeModel.reload() returned invalid response",
+        context: {
+          "url": url,
+          "statusCode": response.statusCode.toString(),
+          "data": response.data?.toString() ?? "null",
+          "valid": response.isValid().toString(),
+        }
+      );
+
       return false;
+
     }
 
     jsondata = response.data;
@@ -200,8 +214,20 @@ class InvenTreeModel {
 
     var response = await api.get(url, params: params);
 
-    if (!response.isValid()) {
+    if (!response.isValid() || response.data == null || !(response.data is Map)) {
+
+      await sentryReportMessage(
+        "InvenTreeModel.get() returned invalid response",
+        context: {
+          "url": url,
+          "statusCode": response.statusCode.toString(),
+          "data": response.data?.toString() ?? "null",
+          "valid": response.isValid().toString()
+        }
+      );
+
       return null;
+
     }
 
     return createFromJson(response.data);
@@ -222,7 +248,18 @@ class InvenTreeModel {
     var response = await api.post(URL, body: data);
 
     // Invalid response returned from server
-    if (!response.isValid()) {
+    if (!response.isValid() || response.data == null || !(response.data is Map)) {
+
+      await sentryReportMessage(
+        "InvenTreeModel.create() returned invalid response",
+        context: {
+          "url": url,
+          "statusCode": response.statusCode.toString(),
+          "data": response.data?.toString() ?? "null",
+          "valid": response.isValid().toString(),
+        }
+      );
+
       return null;
     }