Notice: Undefined index: summary in ./sites/all/modules/microdata/microdata.module on line 440
Warning: array_merge() [function.array-merge]: Argument #2 is not an array in ./sites/all/modules/microdata/microdata.module on line 440

To Reproduce:
Enable Microdata Module and Field Collection
Create a Field Collection with a Long Text (not Long Text w Summary, as this is how I fixed the problem).
Under Manage Display->Custom Display for the Field Collection, enable both Tokens and Full Content.
Select the Tokens option to modify that Display.
Under the settings for Long Text, trim text to a custom value (Here is where the error occurs).
Now if you create a View of Unformatted List for a Node that uses this Field Collection and select Token as the View option under the Field Collection field, the above error populates the preview area.

The Fix:
Remove the Long Text field for the Field Collection.
Add a Long Text w Summary field to replace the field above.
Bam, no error... it's something to do with it getting trimmed. Sorry I can't be of more help.