fixes #735 null pointer issue.

src/metabase/models/common.clj

@@ -31,9 +31,10 @@
     (name->human-readable-name \"admin_users\") -> \"Admin Users\""
   [^String n]
   (when (seq n)
-    (when-let [n (some-> n
-                   (s/replace #"(?:-|_id)$" "")                                       ; strip off any trailing _id or -id suffix
-                   (s/split #"_|-"))]                                                 ; explode string on underscores and hyphens
+    (when-let [n (->> (some-> n
+                        (s/replace #"(?:-|_id)$" "")                                       ; strip off any trailing _id or -id suffix
+                        (s/split #"_|-"))
+                   (filterv not-empty)) ]                                                 ; explode string on underscores and hyphens
       (->> (for [[first-letter & rest-letters] n]                                     ; for each part of the string,
              (apply str (s/upper-case first-letter) (map s/lower-case rest-letters))) ; upcase the first char and downcase the rest
         (interpose " ")                                                               ; add a space between each part

test/metabase/models/common_test.clj

+(ns metabase.models.common-test
+  (:require [expectations :refer :all]
+            [metabase.db :refer :all]
+            [metabase.models.common :refer [name->human-readable-name]]
+            [metabase.test.data :refer :all]))
+
+
+;; testing on `(name->human-readable-name)`
+(expect nil (name->human-readable-name nil))
+(expect nil (name->human-readable-name ""))
+(expect "" (name->human-readable-name "_"))
+(expect "" (name->human-readable-name "-"))
+(expect "Agent Invite Migration" (name->human-readable-name "_agent_invite_migration"))
+(expect "Agent Invite Migration" (name->human-readable-name "-agent-invite-migration"))
+(expect "Foobar" (name->human-readable-name "fooBar"))
+(expect "Foo Bar" (name->human-readable-name "foo-bar"))
+(expect "Foo Bar" (name->human-readable-name "foo_bar"))