fix(supervisor): warn on an empty toleration value instead of rejecting it

The previous parser accepted an empty value, so rejecting it would
crash-loop a supervisor on upgrade for a config that worked. Keep parsing
it as an exact match on a valueless taint, and warn at startup since it is
usually a value that resolved empty by accident.

Author: nicktrn

apps/supervisor/src/envUtil.test.ts

@@ -120,12 +120,10 @@ describe("Tolerations", () => {
     ]);
   });
 
-  it("should reject an empty value, and point at the Exists form instead", () => {
-    const result = Tolerations.safeParse("dedicated=:NoSchedule");
-    expect(result.success).toBe(false);
-    expect(result.error?.issues[0]?.message).toBe(
-      'Invalid toleration format (empty value): "dedicated=:NoSchedule". Drop the "=" to tolerate any value of "dedicated".'
-    );
+  it("should keep an empty value as an exact match for a valueless taint", () => {
+    expect(Tolerations.parse("dedicated=:NoSchedule")).toEqual([
+      { key: "dedicated", operator: "Equal", value: "", effect: "NoSchedule" },
+    ]);
 
     expect(Tolerations.parse("dedicated:NoSchedule")).toEqual([
       { key: "dedicated", operator: "Exists", effect: "NoSchedule" },

apps/supervisor/src/envUtil.ts

@@ -123,11 +123,10 @@ export const Tolerations = z.string().transform((val, ctx) => {
 
       const value = keyValue.slice(eqIdx + 1).trim();
       if (!value) {
-        ctx.addIssue({
-          code: z.ZodIssueCode.custom,
-          message: `Invalid toleration format (empty value): "${entry}". Drop the "=" to tolerate any value of "${key}".`,
-        });
-        return z.NEVER;
+        logger.warn(
+          'Toleration has an empty value, so it matches only a taint whose value is also empty. Drop the "=" to tolerate any value of this key.',
+          { entry, key }
+        );
       }
 
       if (!isLabelValue(value)) {