From 64628d64f2d34f9a7f641d25acb04a1e1c8fdf26 Mon Sep 17 00:00:00 2001
From: Maxim <me@alzhanov.ru>
Date: Wed, 15 May 2024 23:56:25 +0300
Subject: [PATCH] Fixes

---
 src/visualizers/turing-machine/render.tsx        | 13 ++++++++-----
 src/visualizers/turing-machine/turing-machine.ts |  2 +-
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/src/visualizers/turing-machine/render.tsx b/src/visualizers/turing-machine/render.tsx
index c5a3578..8ad3f3d 100644
--- a/src/visualizers/turing-machine/render.tsx
+++ b/src/visualizers/turing-machine/render.tsx
@@ -11,12 +11,10 @@ export const TuringMachineRender = ({ curState, curEvent }: SafeRenderProps<Turi
     const program = curState.program
     const cy = useRef<cytoscape.Core | null>(null)
     const graphRef = useRef<HTMLDivElement>(null)
-    if (curEvent.name === "error") {
-        return <div>
-            Error while running: {curEvent.error + ""}
-        </div>
-    }
     useEffect(() => {
+        if (graphRef.current === null) {
+            return
+        }
         cy.current = cytoscape({
             container: graphRef.current,
             elements: [],
@@ -125,6 +123,11 @@ export const TuringMachineRender = ({ curState, curEvent }: SafeRenderProps<Turi
             console.log(cy.current?.elements())
         }
     }, [JSON.stringify(program)])
+    if (curEvent.name === "error") {
+        return <div>
+            Error while running: {curEvent.error + ""}
+        </div>
+    }
     return <div>
         {curState.machineState.description}
         <br/>
diff --git a/src/visualizers/turing-machine/turing-machine.ts b/src/visualizers/turing-machine/turing-machine.ts
index 82215f3..363bca4 100644
--- a/src/visualizers/turing-machine/turing-machine.ts
+++ b/src/visualizers/turing-machine/turing-machine.ts
@@ -131,7 +131,7 @@ export const turingMachine = async (program: Readonly<string>, startTape: Readon
         for(const rule of parsed.rules) {
             if (state.state === rule.curState && tapeCopy.get(state.curPosition) === rule.curTape) {
                 if (matchingRule !== null) {
-                    throw new Error("Two rules match this state.")
+                    throw new Error(`Two rules match state ${state.state} by symbol ${rule.curTape}: ${matchingRule} and ${rule}.`)
                 }
                 matchingRule = rule
             }