Move validation to the top

Better to fail as soon as possible.

Signed-off-by: Leandro Lucarella <[email protected]>

Author: llucax

src/frequenz/channels/util/_timer.py

@@ -417,6 +417,11 @@ def __init__(
             ValueError: if `interval` is not positive or is smaller than 1
                 microsecond.
         """
+        if interval < timedelta(microseconds=1):
+            raise ValueError(
+                f"The `interval` must be positive and at least 1 microsecond, not {interval}"
+            )
+
         self._interval: int = _to_microseconds(interval)
         """The time to between timer ticks."""
 
@@ -464,12 +469,6 @@ def __init__(
         to wait again.
         """
 
-        if self._interval <= 0:
-            raise ValueError(
-                "The `interval` must be positive and at least 1 microsecond, "
-                f"not {interval} ({self._interval} microseconds)"
-            )
-
         if auto_start:
             self.reset()