Fix unsubscribe not properly unlinking

specs/cells.spec.ts

@@ -100,6 +100,25 @@ describe("Consistent updates", () => {
         runRules(); see("43, 45");
         common();
     })
+    it("handles conditional indirect resubscribes", () => {
+        // Given two rules conditionally subscribed indirectly to the same value
+        const condition = value(false), commonVal = value(42);
+        const indirect = cached(() => void log(commonVal()));
+        rule(() => { if (condition()) commonVal(); });
+        rule(() => { if (condition()) indirect()});
+        runRules(); see();
+        // When the condition is turned on...
+        condition.set(true); runRules(); see("42");
+        commonVal.set(66); runRules(); see("66");
+        commonVal.set(17); runRules(); see("17");
+        // off...
+        condition.set(false); runRules(); see();
+        commonVal.set(42); runRules(); see();
+        // and on again
+        condition.set(true); runRules(); see("42");
+        // Then the indirect calculation should be subscribed again
+        commonVal.set(66); runRules(); see("66");
+    });
     it("with different-length paths to common element", () => {
         const start = value(22);
         const indirect = cached(() => start() * 1.5);

src/cells.ts

@@ -1,7 +1,7 @@
 import { Context, current, makeCtx, swapCtx } from "./ambient.ts";
 import { type RuleQueue, currentRule, ruleQueue, defaultQ } from "./scheduling.ts";
 import { Job, OptionalCleanup, RecalcSource } from "./types.ts"
-import { detached, getJob, makeJob } from "./tracking.ts";
+import { getJob, makeJob } from "./tracking.ts";
 import { Connection, Inlet, IsStream, Sink, Source, backpressure } from "./streams.ts";
 import { setMap } from "./utils.ts";
 import { isError, isValue, markHandled } from "./results.ts";
@@ -11,7 +11,7 @@ import { nullCtx } from "./internals.ts";
  * Error indicating a rule has attempted to write a value it indirectly
  * depends on, or which has already been read by another rule in the current
  * batch. (Also thrown when a cached function attempts to write a value at all,
- * directly or inidirectly.)
+ * directly or indirectly.)
  *
  * @category Errors
  */
@@ -373,6 +373,7 @@ export class Cell {
         if (sub.nT) sub.nT.pT = sub.pT;
         if (sub.pT) sub.pT.nT = sub.nT;
         if (this.subscribers === sub) this.subscribers = sub.nT;
+        sub.nT = sub.pT = undefined;
         if (!this.subscribers) {
             if (this.flags & Is.Calc) {
                 for(let s=this.sources; s; s = s.nS) s.src.unsubscribe(s);