Return more descriptive error for german data query (data too old)

[bart1]

The old error:

Requested data is too old, only the last 3 days are available

library(getRad)
pvol <- get_pvol("dedrs", as.POSIXct("2012-05-17 14:00", tz = "UTC"))
#> Error in `get_pvol()`:
#> ! The server returned an unexpected number of files

^{Created on 2025-09-29 with reprex v2.1.1}

This is the new error:

devtools::load_all("~/getRad")
#> ℹ Loading getRad
pvol <- get_pvol("dedrs", as.POSIXct("2012-05-17 14:00", tz = "UTC"))
#> Error in `get_pvol()`:
#> ✖ The server returned an unexpected number of files.
#> ℹ In many cases this because no data is available for the time requested. For
#>   Germany only the last three days are available.
#> ℹ Alternatively there is an unstable connection or temporal error in the german
#>   data provided.

^{Created on 2025-09-29 with reprex v2.1.1}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.21%. Comparing base (a82add8) to head (e3b9775).
⚠️ Report is 15 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #132      +/-   ##
==========================================
- Coverage   92.66%   92.21%   -0.46%     
==========================================
  Files          24       24              
  Lines        1472     1733     +261     
==========================================
+ Hits         1364     1598     +234     
- Misses        108      135      +27     

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[PietrH]

Can you keep this in draft until it's ready to review?

[bart1]

Sorry it was ready to review but i merged changes from main to see how the code formatter worked :)

[PietrH]

Two small notes, non blocking for merging.

• I suggest renaming the error class.
• I suggest making the skip even more strict so we also skip the test if the data provider is offline. But it's worth staying consistent for all tests in the package.