fix: check store keys length before accessing (#9639)

* check store keys length before accessing

* check store keys length in all modules

* add changelog

* refactoring

* address review comments

* remove commented lines

* small fixes

* address review comments

* fix failing tests

* add godocs

types/kv/helpers.go

@@ -0,0 +1,17 @@
+package kv
+
+import "fmt"
+
+// AssertKeyAtLeastLength panics when store key length is less than the given length.
+func AssertKeyAtLeastLength(bz []byte, length int) {
+	if len(bz) < length {
+		panic(fmt.Sprintf("expected key of length at least %d, got %d", length, len(bz)))
+	}
+}
+
+// AssertKeyLength panics when store key length is not equal to the given length.
+func AssertKeyLength(bz []byte, length int) {
+	if len(bz) != length {
+		panic(fmt.Sprintf("unexpected key length; got: %d, expected: %d", len(bz), length))
+	}
+}