New NoTimeError exception

This is raised when step.time cannot be found.

Author: amorison

stagpy/_step.py

@@ -343,6 +343,8 @@ def __delitem__(self, name):
 
     @crop
     def _header(self) -> Optional[Dict[str, Any]]:
+        if self.step.isnap is None:
+            return None
         binfiles = self.step.sdat._binfiles_set(self.step.isnap)
         header = None
         if binfiles:
@@ -570,14 +572,16 @@ def timeinfo(self) -> Series:
         return info
 
     @property
-    def time(self) -> Optional[float]:
+    def time(self) -> float:
         """Time of this time step."""
         steptime = None
         try:
             steptime = self.timeinfo['t']
         except error.MissingDataError:
             if self.isnap is not None:
                 steptime = self.geom._header.get('ti_ad')
+        if steptime is None:
+            raise error.NoTimeError(self)
         return steptime
 
     @property

stagpy/error.py

@@ -48,6 +48,19 @@ def __init__(self, step: Step):
         super().__init__(f"no geometry info found for {step!r}")
 
 
+class NoTimeError(StagpyError):
+    """Raised when no time can be found for a step.
+
+    Attributes:
+        step: the :class:`~stagpy._step.Step` instance for which no geometry
+            was found.
+    """
+
+    def __init__(self, step: Step):
+        self.step = step
+        super().__init__(f"no time found for {step!r}")
+
+
 class NoRefstateError(StagpyError):
     """Raised when no refstate output can be found.