Confusing error handling when adding vector data store

When adding a Vector data store with erroneous data, Geoserver returns confusing error messages that do not aide the user in diagnosing the problem.

Note: This is a 'batch' bug report. I'll break them up into multiple bugs if desired.

To reproduce the following errors, first perform the following:
1) Login to Geoserver and click the "Stores" link on the left hand side of the page. You should be presented with a list of stores already registered in Geoserver.
2) Scroll down to the bottom of this page, and choose a workspace in the dropdown box titled "Add new store into workspace". I chose the 'topp' workspace.
3) After being shown the list of store types, choose the "Directory of spatial files" at the top of the page. You should now be shown the page containing the confusing error handling.

Error "Field 'paramValue' is required.":
1) After performing the steps above, leave the "Data source name" blank, the "URL" blank or the "namespace" blank, and click 'Save'. For each, you should be shown the error "Field 'paramValue' is required." (As opposed to "URL is required.")

Url must have a slash at the end ("Error creating data store, check the parameters. Error message: null")
1) After performing the steps above, enter "http://www.google.com" in the URL field, and enter valid data in all of the other fields.
2) Click save. Notice you are given the error: "Error creating data store, check the parameters. Error message: null"
3) Add a '/' at the end of the URL (making it "http://www.google.com/") and click save. Notice that the store is created successfully.