Add form validation feedback

[flibbertigibbet]

If a user enters invalid data in a parameters control form, the chart simply fails to reload.

Provide feedback, either as text or with a red border to the form control, or both, so the user may see that the form is invalid.

See #230.

[jfrankl]

@flibbertigibbet I am trying to understand this issue better. Could you give me 2–3 examples of invalid input? For each:

• Name of indicator
• Expected input range
• Input that would trigger an error

[flibbertigibbet]

As with #230:

• percentile low temperature
• integers range 0 to 100
• numbers typed in outside of range or with a decimal point component

[jfrankl]

Does something like this work?

[fungjj92]

I think that's a great visual

[CloudNiner]

Does the red error text fill existing empty space, such that all the components below it don't shift down when the error displays? Otherwise agreed, looks great.

[jfrankl]

@CloudNiner What do you think of something like this, so we don't need to worry about the error message pushing down other content?

[CloudNiner]

That seems good too, as long as the white text on red is readable. It feels very thin but that may just be the screenshot.

[maurizi]

Styling for error popovers was added in #342, but we should still add validation to the rest of the controls