.

wcfs/δbtail.go

@@ -528,7 +528,7 @@ type rangeSplit []*nodeInRange // key↑
 func (rs rangeSplit) Get(k Key) *nodeInRange {
 	rnode, ok := rs.Get_(k)
 	if !ok {
-		panicf("key %v not covered", k)
+		panicf("key %v not covered;  coverage: %s", k, rs)
 	}
 	return rnode
 }
@@ -544,7 +544,7 @@ func (rs rangeSplit) Get_(k Key) (rnode *nodeInRange, ok bool) {
 
 	rn := rs[i]
 	if !(rn.lo <= k && k <= rn.hi_) {
-		panicf("BUG: get(%v) -> %s", k, rn)
+		panicf("BUG: get(%v) -> %s;  coverage: %s", k, rn, rs)
 	}
 
 	return rn, true
@@ -563,7 +563,7 @@ func (prs *rangeSplit) Expand(rnode *nodeInRange) (children rangeSplit) {
 		return rnode.hi_ <= rs[i].hi_
 	})
 	if i == len(rs) || rs[i] != rnode {
-		panicf("%s not in rangeSplit", rnode)
+		panicf("%s not in rangeSplit;  coverage: %s", rnode, rs)
 	}
 
 	// [i].Key ≤ [i].Child.*.Key < [i+1].Key  i ∈ [0, len([]))