Describe the bug

If you add a v-b tooltip to an element without setting a title, an empty tooltip is displayed above the element. I think in earlier versions, the tooltip was hidden until the title was set.

Example:

Steps to reproduce the bug

Create a button with an empty tooltip:
<b-button v-b-tooltip>Test</b-button>
or
<b-button v-b-tooltip="undefined">Test</b-button>
or
<b-button v-b-tooltip="null">Test</b-button>

Expected behavior

The tooltip is only displayed if a title has been set

Versions

Libraries:

• BootstrapVue: 2.0.0
• Bootstrap: 4.3.1
• Vue: 2.6.10

Environment:

• Device: Mac
• OS: macOS Mojave
• Browser: Chrome
• Version: 76