fix: convert some warnings to errors

lua/git/object.lua

@@ -268,7 +268,7 @@ end
 local function load_blob(r, blob, path, sha)
     local buf = blob_buf(r, blob, path, sha)
     if not buf then
-        util.warning("no content for %s at %s", path, sha)
+        util.error("no content for %s at %s", path, sha)
         return
     end
     vim.cmd.normal({ "m'", bang = true })
@@ -279,7 +279,7 @@ end
 ---@param section ow.Git.DiffSection
 local function open_section(s, section)
     if not section.blob_a or not section.blob_b then
-        util.warning("no index line, cannot determine blob SHAs")
+        util.error("no index line, cannot determine blob SHAs")
         return
     end
     local parent = s.parent_sha or "0"
@@ -291,7 +291,7 @@ local function open_section(s, section)
         return
     end
     if not left and not right then
-        util.warning("no content for %s", section.path_b)
+        util.error("no content for %s", section.path_b)
         return
     end
     local buf = left or right
@@ -319,7 +319,7 @@ function M.open(r, rev, opts)
         { cwd = r.worktree, silent = true }
     )
     if not content then
-        util.warning("not a git object: %s", rev)
+        util.error("not a git object: %s", rev)
         return
     end
     local buf = M.buf_for(r, parsed, content)