Fix initial flow

trustgraph-flow/trustgraph/bootstrap/initialisers/default_flow_start.py

@@ -49,6 +49,14 @@ class DefaultFlowStart(Initialiser):
 
     async def run(self, ctx, old_flag, new_flag):
 
+        workspaces = await ctx.config.keys(
+            "__workspaces__", "workspace",
+        )
+        if self.workspace not in workspaces:
+            raise RuntimeError(
+                f"Workspace {self.workspace!r} does not exist yet"
+            )
+
         flow = ctx.make_flow_client(self.workspace)
         await flow.start()