[widgets][toolchaineditor] add default color channel if none found

beat/editor/widgets/toolchaineditor.py

@@ -389,7 +389,7 @@ class Connection(QGraphicsPathItem):
         self.end_pin_name = connection_details["to"].split(".")[1]
         self.channel = connection_details["channel"]
 
-        if self.channel is None or self.channel not in channel_colors:
+        if self.channel is None:
             warning = QMessageBox()
             warning.setIcon(QMessageBox.Warning)
             warning.setWindowTitle(toolchain.tr("Connection creation"))
@@ -400,6 +400,21 @@ class Connection(QGraphicsPathItem):
             warning.exec_()
 
         else:
+            if self.channel not in channel_colors:
+                toolchain.web_representation["channel_colors"][self.channel] = "#000000"
+                channel_colors = toolchain.web_representation["channel_colors"]
+
+                warning = QMessageBox()
+                warning.setIcon(QMessageBox.Warning)
+                warning.setWindowTitle(toolchain.tr("Channel color"))
+                warning.setInformativeText(
+                    toolchain.tr(
+                        "No channel color found. Assigning default black color"
+                    )
+                )
+                warning.setStandardButtons(QMessageBox.Ok)
+                warning.exec_()
+
             hexadecimal = channel_colors[self.channel].lstrip("#")
             hlen = len(hexadecimal)
             self.connection_color = list(