Add more information to unexpected assertion failure

Issue: #4532

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=208968252

library/core/src/main/java/com/google/android/exoplayer2/upstream/DefaultAllocator.java

@@ -118,8 +118,18 @@ public final class DefaultAllocator implements Allocator {
     }
     for (Allocation allocation : allocations) {
       // Weak sanity check that the allocation probably originated from this pool.
-      Assertions.checkArgument(allocation.data == initialAllocationBlock
-          || allocation.data.length == individualAllocationSize);
+      if (allocation.data != initialAllocationBlock
+          && allocation.data.length != individualAllocationSize) {
+        throw new IllegalArgumentException(
+            "Unexpected allocation: "
+                + System.identityHashCode(allocation.data)
+                + ", "
+                + System.identityHashCode(initialAllocationBlock)
+                + ", "
+                + allocation.data.length
+                + ", "
+                + individualAllocationSize);
+      }
       availableAllocations[availableCount++] = allocation;
     }
     allocatedCount -= allocations.length;