Running examples in 'forestr-Ex.R' failed
The error most likely occurred in:

> ### Name: calc_tls_mean_leaf_ht
> ### Title: Process single PCL transects.
> ### Aliases: calc_tls_mean_leaf_ht
> ### Keywords: processing tls
> 
> ### ** Examples
> 
> 
> # with designated file
> ## Not run: process_pcl("pcl_data.csv", marker.spacing = 10, user_height = 1.05, max.vai = 8)
> 
> 
> # with data frame
> process_pcl(osbs, marker.spacing = 10, user_height = 1.05, max.vai = 8)
Transect Length
[1] 40
Table of sky hits

FALSE  TRUE 
 3048  7458 
RAW LiDAR metrics -- WARNING
Mean Return Height (m) of raw data
[1] 10.76431
Standard Deviation of raw  Canopy Height returns-- meanStd in old code
[1] 3.569992
Max Measured Canopy Height (m)
[1] 14.827
Scan Density
[1] 262.65
OPENNESS AND COVER METRICS
Sky Fraction (%)
[1] 71.02181
Cover Fraction (%)
[1] 28.97819
Rumple
[1] 2.125
Mean Gap Fraction ---as error check should be same as porosity
[1] 0.928125
now we replace the 0's with 1's so when we take the ln they = 0
Clumping Index
[1] 0.9823258
Transect Length (m)
[1] 40
HEIGHT METRICS
Mean Leaf Height (H) - plot mean of column mean leaf height
[1] 4.205116
Height2 (H[2]) - standard deviation of column mean leaf height
[1] 5.614907
Mean Leaf Height variance (H[var]) - variance of column mean leaf height
[1] 31.52718
Root Mean Square Mean Leaf Height (H[rms]) - the root mean square or quadratic mean of column mean leaf height for the transect
[1] 6.958592
Max canopy height (m)
[1] 14.827
Mean Outer Canopy Height (m) or MOCH
[1] 4.4666
AREA AND DENSITY METRICS
Mean VAI - mean VAI for entire transect
[1] 1.506926
Mean Height of VAI[max] - modeEl
[1] 3.975
Mode 2- The standard deviation of VAImax or MaxEl
[1] 5.35646
Maximum VAI for entire transect -- max el!
[1] 5.75966
Mean Peak VAI for entire transect
[1] 0.9317552
CANOPY AND OPENNESS METRICS (cont.)
Deep Gaps
[1] 24
Deep Gap Fraction (0-1)
[1] 0.6
ARRANGEMENT METRICS
Canopy porosity
[1] 0.928125
Square of leaf height variance (stdStd from old script)
[1] 0.4566521
Mean Standard deviation of leaf heights -- meanStd
[1] 0.2439959
Canopy Rugosity
[1] 0.6301731
Surface Rugosity--TopRugosity
[1] 5.861305
Effective Number of Layers:  
[1] 11.02083
[1] "_output"
[1] "./output/"
No. of NA values in hit matrix
[1] 594
Error in stats::approxfun(x_in, lab_in[, 1]) : 
  need at least two non-NA values to interpolate
Calls: process_pcl ... seq_gradient_pal -> gradient_n_pal -> colour_ramp -> <Anonymous>
Execution halted