Fix CodeQL useless-comparison alert in XorFilter construction loop

Hoist the construction-failure throw out of the peeling loop so the loop can terminate through its own bound. Previously the last iteration always exited via break or throw, making the 'attempt < MAX_ITERATIONS' condition provably always-true (CodeQL java/constant-comparison). Behavior is unchanged; the success check now runs after the loop.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/main/java/org/apache/datasketches/filters/xorfilter/XorFilter.java

diff --git a/src/main/java/org/apache/datasketches/filters/xorfilter/XorFilter.java b/src/main/java/org/apache/datasketches/filters/xorfilter/XorFilter.java
index 5c48eeb..96ffb4f 100644
--- a/src/main/java/org/apache/datasketches/filters/xorfilter/XorFilter.java
+++ b/src/main/java/org/apache/datasketches/filters/xorfilter/XorFilter.java
@@ -131,10 +131,10 @@
       buildSeed = splitMix64(rngState);
       stackSize = map(keys, numKeys, buildSeed, xorMask, count, queue, stackHash, stackIndex);
       if (stackSize == numKeys) { break; }
-      if (attempt == (MAX_ITERATIONS - 1)) {
-        throw new SketchesArgumentException("Xor filter construction failed after " + MAX_ITERATIONS
-            + " attempts; the input likely contains duplicate keys or is degenerate.");
-      }
+    }
+    if (stackSize != numKeys) {
+      throw new SketchesArgumentException("Xor filter construction failed after " + MAX_ITERATIONS
+          + " attempts; the input likely contains duplicate keys or is degenerate.");
     }
 
     seed_ = buildSeed;