Python: generate markdown for error types.

source/python/README.md

@@ -51,7 +51,7 @@ dates and times represented by `Time` objects.
 ---
 
 <a name="ApsisKind"></a>
-### ApsisKind
+### enum ApsisKind
 
 **Represents whether a satellite is at a closest or farthest point in its orbit.**
 
@@ -72,7 +72,7 @@ two cases applies to a particular apsis event.
 ---
 
 <a name="Body"></a>
-### Body
+### enum Body
 
 **The celestial bodies supported by Astronomy Engine calculations.**
 
@@ -96,7 +96,7 @@ two cases applies to a particular apsis event.
 ---
 
 <a name="Direction"></a>
-### Direction
+### enum Direction
 
 **Indicates whether a body is rising above or setting below the horizon.**
 
@@ -115,7 +115,7 @@ and `Direction.Set` is used to find sunset times.
 ---
 
 <a name="Refraction"></a>
-### Refraction
+### enum Refraction
 
 **Selects if/how to correct for atmospheric refraction.**
 
@@ -131,6 +131,91 @@ as seen by an observer on the surface of the Earth.
 | `JplHorizons` | Used only for compatibility testing with JPL Horizons online tool. |
 
 
+---
+
+<a name="errors"></a>
+## Error Types
+
+
+---
+
+<a name="BadVectorError"></a>
+### BadVectorError
+
+A vector magnitude is too small to have a direction in space.
+
+
+
+
+
+---
+
+<a name="EarthNotAllowedError"></a>
+### EarthNotAllowedError
+
+The Earth is not allowed as the celestial body in this calculation.
+
+
+
+
+
+---
+
+<a name="Error"></a>
+### Error
+
+Indicates an error in an astronomical calculation.
+
+
+
+
+
+---
+
+<a name="InternalError"></a>
+### InternalError
+
+**An internal error occured that should be reported as a bug.**
+
+Indicates an unexpected and unrecoverable condition occurred.
+If you encounter this error using Astronomy Engine, it would be very
+helpful to report it at the [Issues](https://github.com/cosinekitty/astronomy/issues)
+page on GitHub. Please include a copy of the stack trace, along with a description
+of how to reproduce the error. This will help improve the quality of
+Astronomy Engine for everyone! (Thank you in advance from the author.)
+
+
+
+
+
+---
+
+<a name="InvalidBodyError"></a>
+### InvalidBodyError
+
+The celestial body is not allowed for this calculation.
+
+
+
+
+
+---
+
+<a name="NoConvergeError"></a>
+### NoConvergeError
+
+**A numeric solver did not converge.**
+
+Indicates that there was a failure of a numeric solver to converge.
+If you encounter this error using Astronomy Engine, it would be very
+helpful to report it at the [Issues](https://github.com/cosinekitty/astronomy/issues)
+page on GitHub. Please include a copy of the stack trace, along with a description
+of how to reproduce the error. This will help improve the quality of
+Astronomy Engine for everyone! (Thank you in advance from the author.)
+
+
+
+
 ---
 
 <a name="functions"></a>

source/python/astronomy.py

@@ -157,26 +157,48 @@ _PlanetOrbitalPeriod = [
 ]
 
 class Error(Exception):
+    """Indicates an error in an astronomical calculation."""
     def __init__(self, message):
         Exception.__init__(self, message)
 
 class EarthNotAllowedError(Error):
+    """The Earth is not allowed as the celestial body in this calculation."""
     def __init__(self):
         Error.__init__(self, 'The Earth is not allowed as the body.')
 
 class InvalidBodyError(Error):
+    """The celestial body is not allowed for this calculation."""
     def __init__(self):
         Error.__init__(self, 'Invalid astronomical body.')
 
 class BadVectorError(Error):
+    """A vector magnitude is too small to have a direction in space."""
     def __init__(self):
         Error.__init__(self, 'Vector is too small to have a direction.')
 
 class InternalError(Error):
+    """An internal error occured that should be reported as a bug.
+
+    Indicates an unexpected and unrecoverable condition occurred.
+    If you encounter this error using Astronomy Engine, it would be very
+    helpful to report it at the [Issues](https://github.com/cosinekitty/astronomy/issues)
+    page on GitHub. Please include a copy of the stack trace, along with a description
+    of how to reproduce the error. This will help improve the quality of
+    Astronomy Engine for everyone! (Thank you in advance from the author.)
+    """
     def __init__(self):
         Error.__init__(self, 'Internal error - please report issue at https://github.com/cosinekitty/astronomy/issues')
 
 class NoConvergeError(Error):
+    """A numeric solver did not converge.
+
+    Indicates that there was a failure of a numeric solver to converge.
+    If you encounter this error using Astronomy Engine, it would be very
+    helpful to report it at the [Issues](https://github.com/cosinekitty/astronomy/issues)
+    page on GitHub. Please include a copy of the stack trace, along with a description
+    of how to reproduce the error. This will help improve the quality of
+    Astronomy Engine for everyone! (Thank you in advance from the author.)
+    """
     def __init__(self):
         Error.__init__(self, 'Numeric solver did not converge - please report issue at https://github.com/cosinekitty/astronomy/issues')
 
@@ -1099,7 +1121,7 @@ def _vector2radec(pos):
     if xyproj == 0.0:
         if pos[2] == 0.0:
             # Indeterminate coordinates: pos vector has zero length.
-            raise Error('Cannot convert vector to polar coordinates')
+            raise BadVectorError()
         ra = 0.0
         if pos[2] < 0.0:
             dec = -90.0