Ensure send slice gas loading state is set to false upon gas estimation error (#11581)

ui/ducks/send/send.js

@@ -1082,6 +1082,11 @@ const slice = createSlice({
           });
         }
       })
+      .addCase(computeEstimatedGasLimit.rejected, (state) => {
+        // If gas estimation fails, we should set the loading state to false,
+        // because it is no longer loading
+        state.gas.isGasEstimateLoading = false;
+      })
       .addCase(GAS_FEE_ESTIMATES_UPDATED, (state, action) => {
         // When the gasFeeController updates its gas fee estimates we need to
         // update and validate state based on those new values